Procedural sedation and analgesia (PSA) is something that the physician treating emergent orthopedic injuries will use frequently. It is not without significant complications, especially when it is performed hastily or without understanding the pharmacology of the medications involved. However, there is a substantial body of literature supporting the safe use of PSA by emergency physicians.13–15
The goal of PSA is to induce a state of tolerance to emergency procedures while preserving airway reflexes. This is usually accomplished by administering a sedative or dissociative agent, as well as an analgesic agent. However, certain fundamental principles must be adhered to well before the first agent is used. Requirements include appropriate personnel, thorough patient assessment and consent, adequate equipment, patient monitoring, and documentation.16 It is only after these requirements are satisfied that the physician can begin to consider drug administration.
PSA should only be performed by an individual who possesses an understanding of the medications used, an ability to monitor the patient’s response, and the skills necessary to address any airway or cardiovascular complications that may occur. In general, this requires a second clinician, other than the physician performing the procedure.
Patient assessment should begin with a past medical history, including anesthetic history, medications, and allergies. PSA in individuals with an American Society of Anesthesiology Physical Status Class III (severe systemic disease with definite functional limitation) or higher should be avoided. Specific fasting periods before procedural sedation are not supported by the available medical literature and the traditional guideline of 2 hours after clear liquids and 6 hours after solids and other liquids is not always practical in the ED, as often the procedure in question cannot be delayed.17–19 A prospective, observational study of 1014 children identified no difference in airway complications, emesis, or other adverse events between patients who met and did not meet the fasting guidelines. Moreover, no aspiration events were noted in either group. However, the authors did note that the study was underpowered to fully detect differences in rates of emesis due to the extremely rare nature of such events.20 Therefore, while recent food intake is not a contraindication to administering procedural sedation, it should be considered in targeting the depth of sedation.16
Necessary equipment includes oxygen, suction, advanced life support equipment, and appropriate reversal agents (when applicable). Intravenous access should be established and the patient should be placed on a monitor with continuous pulse oximetry and capnometry, if available. Supplemental oxygen via a nasal cannula, though controversial in the literature, is generally recommended. A departmentally developed checklist will help ensure compliance and will improve documentation.21
There are a numerous options for PSA in the ED, which include midazolam, fentanyl, ketamine, etomidate, propofol, and various combinations of these medications. The ideal agent varies depending upon the clinical circumstances. Whichever agents are used, a key to safe administration involves slow titration of the drug until the desired effect is achieved.16,22 Rapid administration may lead to a higher rate of complications including hypotension and respiratory depression. A review of the most commonly used agents as well as reversal agents is provided in Table 2–1.
TABLE 2–1Procedural Sedation Medications and Reversal Agents ||Download (.pdf) TABLE 2–1 Procedural Sedation Medications and Reversal Agents
|Agent ||Initial IV Dose ||Duration (min) ||Important Complications |
|Midazolam (Versed) ||0.05 mg/kg every 3–5 min ||30–60 ||Respiratory depression, hypotension |
|Fentanyl (Sublimaze) ||0.5–1.0 μg/kg every 3–5 min ||20–30 ||Respiratory depression, hypotension, rigid chest syndrome |
|Ketamine (Ketalar) ||0.5–1.0 mg/kg ||45 ||Increased secretions, emergence reactions, laryngospasm, elevated ICP |
|Etomidate (Amidate) ||0.1 mg/kg ||20 ||Myoclonus (up to 20%), respiratory depression, vomiting |
|Methohexital (Brevital) ||1–1.5 mg/kg ||5–7 ||Respiratory depression, fasciculations, burning at IV site |
|Propofol (Diprivan) ||1.0 mg/kga ||3–5 ||Respiratory depression, hypotension |
|Naloxone (Narcan) ||0.1 mg/kg ||20–40 ||Resedation, agitation |
|Flumazenil (Romazicon) ||0.02 mg/kg ||20–40 ||Resedation, seizures |
This agent should be dosed in increments of 0.05 mg/kg (up to 1–2 mg increments in adults) every 3 to 5 minutes to get the desired effect. A dose of 0.1 mg/kg will usually produce sedation within 2 to 3 minutes. This agent is the ideal benzodiazepine for procedural sedation due to its amnestic properties, as well as its short duration of action (30–60 minutes). The most important complication from midazolam use is respiratory depression. This effect appears to be augmented in patients receiving concomitant opioids or who have underlying pulmonary disease. Other adverse reactions include hypotension, vomiting, hallucinations, and hiccups. Of note, 1% of children under the age of 5 may experience paradoxical excitation which can be reversed with flumazenil.23
This agent is the preferred opioid for procedural sedation due to its rapid onset and short duration of action. Peak analgesia is accomplished in 2 to 3 minutes and the duration of action is only 20 to 30 minutes. It is recommended to use incremental doses of 1 μg/kg IV in adults and children, given slowly to a total dose of 2 to 3 μg/kg. Fentanyl is contraindicated in children younger than 6 months because of the risk of severe laryngospasm. In addition to respiratory depression and hypotension, fentanyl is also associated with chest wall rigidity. Rigid chest syndrome appears to occur at very high doses (>15 μg/kg) when the drug is administered rapidly.
This agent has dissociative properties and is one of the most commonly used anesthetic agents for procedural sedation. Patients who have been administered this drug have blunted sensory perceptions and no memory of the events. Ketamine is advantageous for procedural sedation because it is not associated with a loss of protective airway reflexes and is the only sedative that also has analgesic properties. The recommended dose is 1 to 2 mg/kg intravenously. The onset of action is 1 minute with duration of 45 minutes. Contraindications include age less than 3 months, increased intraocular pressure, cardiovascular disease, or active respiratory infections. Adverse reactions include increased respiratory secretions, emergence reactions, and laryngospasm. Administering atropine or glycopyrrolate at 0.01 mg/kg 10 minutes before giving ketamine can decrease the respiratory secretions. Emergence reactions are hallucinations that occur during the recovery period. They are seen in up to 50% of adults and 10% of children. They are rare in children younger than 10 years. Concurrent administration of midazolam is sometimes given with the hope of decreasing the frequency of emergence reactions, although one randomized controlled trial refuted its effectiveness.24 Laryngospasm is a rare complication of ketamine administration that can often be treated with positive pressure ventilation. Rarely, succinylcholine is required for adequate ventilation if laryngospasm is severe or persists. Post-recovery nausea and vomiting may occur and can generally be treated with antiemetics, such as ondansetron.
This agent is a nonbarbiturate, imidazole hypnotic that has been gaining popularity for procedural sedation in the ED due to its rapid onset (30–60 seconds), short duration, and low side-effect profile. A dose of 0.1 mg/kg is given slowly with additional doses of 0.05 mg/kg given every 3 to 5 minutes until appropriate sedation is achieved. Ninety-five percent of patients obtain full recovery within 30 minutes of administration.25 Side effects include respiratory depression, myoclonus, vomiting, and pain with injection.25–27 Myoclonus occurs in up to 20% of patients and is usually mild and self-limited, but occasionally may interfere with the procedure.14,28 Etomidate has not been shown to produce seizure activity when observed by an electroencephalogram.29 Respiratory depression, as represented by an oxygen saturation of <94%, occurs in 3% to 8% of patients.22,24–27 Adrenocortical dysfunction is transient and the clinical significance of this finding is unclear.30 Some authors recommend caution when using this agent in patients with septic shock, but it is unlikely to be clinically significant in the ED PSA setting.31
Methohexital is an ultrashort-acting barbiturate. One of the advantages of methohexital is that it has a rapid onset with maximal sedation in less than 1 minute in most cases. The initial dose is 1 to 1.5 mg/kg followed by repeat doses of 0.5 mg/kg every 3 to 5 minutes as needed for further sedation. Alteration in hemodynamics is unusual, but respiratory depression is not uncommon. In one study of 76 adult patients, methohexital caused apnea in eight patients (10.5%) for an average duration of 64 seconds. Bag-valve mask ventilation was required in these patients, but none needed intubation.32 In another study, 4 of 52 patients (8%) receiving methohexital required bag-valve mask ventilation.33
Propofol is a nonopioid, nonbarbiturate, sedative-hypnotic agent that can be administered at an initial dose of 0.5 to 1.0 mg/kg. Others prefer to give smaller initial amounts (10–20 mg intravenous push every 30 seconds until adequate sedation is achieved). This avoids overshooting with your initial bolus. Subsequent maintenance dosing can be as a continuous infusion or with 0.25 to 0.5 mg/kg boluses every 3 minutes as needed.34 Propofol is remarkable because it produces a very rapid onset (approximately 45 seconds) of a deep and effective sedation with a short duration (3–5 minutes). When compared with midazolam/fentanyl, both onset and duration are significantly shorter.35 Additional benefits are its potent antiemetic properties and its ability to reduce intracranial pressure. This must be balanced against the propensity of propofol to cause transient decreases in blood pressure, though the significance in otherwise healthy patients is debatable.
The depth of sedation provided by propofol requires extra vigilance in the observation of the patient to detect early complications, respiratory compromise, and hypotension.35,36 In one study, the rate of oxygen desaturation was 8% and assisted ventilation with bag-valve mask was 4%.36 In the only study to compare propofol with etomidate, rates of bag-valve mask use, airway repositioning, and stimulation to induce breathing were the same.36 Intravenous fluids should be available to administer if the patient becomes hypotensive during the use of propofol.37 Despite these potential problems, multiple studies looking at the use of propofol in the ED have shown it to be safe and cost effective for both adults and children when compared with other agents.38–45
Propofol is a potent amnestic agent that lacks intrinsic analgesic properties. For this reason, it is frequently used with fentanyl, although a lower dose of ketamine (0.3 mg/kg) appears to reduce the rate of adverse events fivefold.46,47 Other authors have noted that because patients who receive only propofol without an analgesic generally have no recollection of the procedure and high satisfaction scores that an accompanying analgesic may not be necessary.40
Ketofol is a newer procedural agent composed of equal amounts of ketamine and propofol. The initial dose ranges from 0.375 to 0.7 mg/kg each of ketamine and propofol, which can either be given individually or mixed together in the same syringe.48–51 The concept behind this mixture was to balance the hypotensive, respiratory depressant, and antiemetic components of propofol with the hypertensive, respiratory drive preserving, emetogenic, and analgesic components of ketamine. When compared with ketamine, there were decreased episodes of vomiting, decreased emergence reactions, greater patient satisfaction, and decreased sedation and recovery times.48 However, when compared with propofol, there appeared to be little difference in respiratory events or patient satisfaction.49 At this time, further studies are needed, but this combination may be utilized more frequently in the future.
This agent will reverse the effects of opioids. An intravenous dose of 1 to 2 mg (0.1 mg/kg in children) will reverse respiratory depression in most situations. Onset is rapid, but duration of action is relatively short (20–40 minutes), so resedation may occur if longer-acting opioids were used.
This agent will reverse the effects of benzodiazepine administration. The intravenous dose in an adult is 0.2 mg over 15 seconds (0.02 mg/kg in a child) that can be repeated at 1-minute intervals until the desired effect is achieved. In a manner similar to naloxone, resedation may occur if the effects of the benzodiazepine outlast the 20- to 40-minute duration of action of flumazenil. It is recommended to use this agent with caution, as it is known to lower the seizure threshold and can produce refractory seizures in chronic benzodiazepine users.
Monitoring in the postprocedure period is still important, as complications may occur following the removal of noxious stimuli. In children, the risk for adverse events is greatest within the first 10 minutes after the administration of a medication and in the immediate postrecovery phase.52 Discharge criteria should include a patient who is conscious and responding appropriately, has normal vital signs, normal respiratory status, and is able to tolerate oral liquids.16